Every USB Card with an RTL8139 chip schould work. You need also USB Adpter Card support from Apple.
The best solution for me was the "LMP All in One" card with FireWire, USB and 100 Mbit Ethernet at one PCI 2.0/2.2 Bus (3,6 and 5 V) It is an Cherry1394 Model 69121 card.
The best solution for me was the "LMP All in One" card with FireWire, USB and 100 Mbit Ethernet at one PCI 2.0/2.2 Bus (3,6 and 5 V) It is an Cherry1394 Model 69121 card.